Added OpenTelemetry instrumentation to Ghost backend

[cmraible]

This PR adds OpenTelemetry instrumentation to Ghost's backend code, which allows us to view traces similar to what we see in Sentry Performance locally.

It also refactors the ConnectionPoolInstrumentation (that was seeming to cause CPU utilization issues) —instead of creating so many logs and metrics and trying to pipe them into elastic, this class now simply creates spans in OpenTelemetry for the acquire and query stage of the query, so you can see both if there is contention in the pool and if the query itself is taking a long time. The new version of this instrumentation lives at ghost/core/core/shared/OpenTelemetryKnexTracing.js.

Note: there is likely some opportunity to combine this file with ghost/core/core/shared/SentryKnexTracingIntegration.js since there is a lot of overlap in functionality, but for now this seems to work well.

OpenTelemetry is enabled if NODE_ENV === 'development' or if it is explicitly enabled via config with opentelemetry:enabled.

It also adds a Jaeger container to Ghost's docker-compose file for viewing the traces. There's no setup required (beyond running yarn docker:reset to pickup the changes in the docker-compose file the first time — but this will also reset your DB so be careful). This will launch the Jaeger container, and you can view the UI to see the traces at http://localhost:16686/search.

Example trace in Jaeger:

Todo:

• Combine OpenTelemetryKnexTracing.js and SentryKnexTracingIntegration.js if it makes sense
• Add more attributes to the tags as needed
• Add tests for unhappy paths and make sure any potential errors are caught
• Check if CPU usage is affected by this

[codecov]

Codecov Report

Attention: Patch coverage is 94.21053% with 11 lines in your changes are missing coverage. Please review.

Project coverage is 73.29%. Comparing base (b6195d2) to head (6845204).
Report is 184 commits behind head on main.

Files	Patch %	Lines
ghost/core/core/shared/OpenTelemetryKnexTracing.js	92.48%	10 Missing ⚠️
ghost/core/core/shared/instrumentation.js	97.72%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #20144      +/-   ##
==========================================
+ Coverage   73.02%   73.29%   +0.27%     
==========================================
  Files        1264     1265       +1     
  Lines       73780    74314     +534     
  Branches     9825     9868      +43     
==========================================
+ Hits        53876    54467     +591     
+ Misses      19103    19047      -56     
+ Partials      801      800       -1     

Flag	Coverage Δ
admin-tests	42.07% <ø> (+0.28%)	⬆️
e2e-tests	81.84% <94.21%> (+0.22%)	⬆️

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[daniellockyer]

Does @opentelemetry/instrumentation-knex not work in place of this?

[cmraible]

It picks up the queries, but it doesn't include spans for the acquire piece. That said, this is pretty ugly and doesn't seem to scale well, so I think we might just have to accept what we get with @opentelemetry/instrumentation-knex as good enough — leaning towards tearing this out at this point.